- Change Alloc to be a Write with a callback that exposes the WritableBuffer.
This allows the ISocketOutput to implementation to not call the callback if
the underlying socket is dead.
- Added a new functional test
- Changed socket output to be based on pipelines
- Changed connection filter glue to be based on pipelines
- Codegen that used `MemoryPoolIterator` for output now uses `WritableBuffer`
- Made `UvWriteReq` async/await friendly with `LibuvAwaitable<T>`
- Deleted MemoryPool and friends
Pavel Krymets
Stephen Halter
David Fowler
Cesar Blum Silveira